re: Brightness scale in decibels.

What units do -88.8 and 0 have? Decibels use a log scale: where is a reference sound and is the sound being measured.
If this is the case then your maximum sound will be equal to the reference sound you used (this could be how you're defining the reference sound)

re: Brightness scale in decibels.

That should read x_b? I was using it to signify units - in this case x_b is the brightness level. If you're not sure you can always draw it on a graph and connect with a straight line.

For inputting on your calculator you should have something similar to a "E" or "10^x" button. If you prefer you can put in 0.001 as 10^(-3) simply means we move the decimal point three places to the left from 1.

Re: Brightness scale in decibels.

Official opinion. You appear not to have sufficient background to handle this problem. Please find someone local with sufficient math skills to help you.

Most importantly, and that's why I posted it first, you must understand that there is not JUST ONE way to proceed. You must find a way, build a way, and understand a way that fits your application and will be of some value.

So far, you are just shooting in the dark. This will not lead to understanding, but is a very nice path to frustration.

Re: Brightness scale in decibels.

No I don't have sufficient background, that's why i came to this forum. I'm not really trying to understand maths here because I'm not a mathematician.

This is a small piece of a bigger project and i just need the formula to proceed so that's why i hoped that one of you guys will be able to help me find the formula I'm looking for.

You have two options. 1. Provide the context of this problem in its entirety, so we can have any chance at all of helping you. 2. Following TKHunny's advice in Post # 10. If your next post in this thread does not contain the context of your problem, I will close the thread.

Re: Brightness scale in decibels.

Hmm. Well, going off of e^(i*pi)'s (generally correct) formula in Post # 4, you cannot get what you need, because 0 is not in the domain of the logarithm function. I propose, therefore, a formula of the form

where is the brightness, and is the decibel rating. Plugging in the two conditions yields the following two equations for m and b: